1. Field of the Invention
The present invention relates generally to syringes of the character used to administer drugs by injecting them into subcutaneous tissue. More particularly, the invention concerns a syringe of novel design in which a first component, such as a sterilized diluent, can be intermixed with a second component, such as a drug to form a beneficial agent which can be dispensed directly from the syringe.
2. Discussion of the Invention
Hypodermic syringes are commonly used for injecting into a patient beneficial agents, such as drugs in liquid form. Typically, the beneficial agent to be injected is drawn into the syringe from another container, such as a glass vial, bottle or the like having a pierceable, self-sealing stopper. When the beneficial agent, such as a pharmaceutical, is in powder form prior to injection, it must be mixed with a carrier liquid or diluent, such as saline solution, dextrose solution and sterilized water.
Mixing of powdered pharmaceuticals with the carrier liquid has been accomplished in several ways, many of them being quite crude. For example, a common practice is to inject a small quantity of the liquid carrier into the vial to dissolve the powdered component. Then, using a cannula and syringe, the solution thus formed is injected into a larger container containing the liquid carrier. This method is quite tedious and provides substantial opportunities for contamination and error.
Because infusion of medicaments is most often accomplished in a hospital environment, it is the nurse, doctor or medical technician who mixes the drug and diluent, usually at a time shortly before administration of the drug to the patient. This mixing step can be time consuming and hazardous, as for example, when toxic drugs are involved. Further, since many of the prior art mixing devices are crude and imprecise, accurate, sterile and thorough mixing of the drug and the diluent is most difficult and time consuming. Accordingly, such devices are not well suited for use in the home environment.
In the past several attempts have been made to provide a syringe apparatus in which separate components can be intermixed prior to patient injection. Exemplary of such prior art devices are those disclosed in U.S. Pat. No. 2,724,383 issued to Lockhart; in U.S. Pat. No. 3,336,924 issued to Sarnoff, et al and U.S. Pat. No. 3,477,432 issued to Shaw. The Lockhart apparatus includes segregating compartments in the form of connecting, interfitting containers with associated cannula means which are manipulatable simultaneously so as to provide intercommunication between the compartments via the cannula means. The components to be mixed are stored in the interfitting containers and then are intermixed by suitably manipulating the containers. The device can be brought into "administering" condition by withdrawal of one of the empty containers to produce a hypodermic syringe type structure.
Sarnoff, et al. discloses several types of syringe packages, each comprising a vial containing a medicament, a stopper closing the vial, a connector member attached to the vial and extending beyond the stopper, and a syringe interconnected to the connector member. In one form of the Sarnoff invention, the needle of the syringes is partially embedded in the stopper. In another form of the invention, a double needle unit is carried within the connector member so that one needle can penetrate the stopper on the vial and the other can penetrate a stopper on a second container. In this last described embodiment, the double needle unit provides the flow path between the vial and the second container so that component mixing can occur.
In the Shaw patent various versions of combined mixing and injecting syringes are disclosed. The Shaw device enables intermixing of two ingredients which may be powders or liquids and provides for the injection of the mixture after the mixing step has been accomplished.
The apparatus of the present invention provides a totally new and novel approach to precisely intermixing two components and then expelling the mixture from the device through a needle or blunt cannula. More particularly, the apparatus comprises a housing within which an immobilized drug cartridge containing a selected drug or other beneficial agent can be inserted. One end of the housing is open and the opposite end is provided with an inwardly extending needle and an outwardly extending blunt end cannula. A diluent assembly including a sealed vial is then inserted into the open end of the housing and urged telescopically inward of the housing. This causes a double ended needle to simultaneously pierce the sealed vial and a rear seal provided on the drug cartridge thereby placing the vial and the drug cartridge in fluid communication. A continued inward force on the diluent assembly will cause the inwardly extending needle of the housing to pierce the forward seal of the drug cartridge, placing the interior of the drug cartridge in fluid communication with the blunt end cannula. As the diluent flows through the drug cartridge, it will controllably intermix with the immobilized drug forming an injectable solution which can be expelled from the device via the blunt ,end cannula.